Permanent metal foundry mold



NOV. 12, 1929. c, w s' 1,734,974

PERMANENT METAL FOUNDRY MOLD Fil s pt- 1928 2 Sheets-Sheet l Nov. 12, 1929. c, LEWIS PERMANENT METAL FOUNDRY MOLD Filed Sept. 7, 1928 2 Sheets-Sheet 2 Patented Nov. 12, 1929 UNITED STATES PATENT OFFICE ERIC CRISP LEWIS, OF TEDDINGTON, ENGLAND, ASSIGNOB, TO THE AUTOMOTIVE EN- GINEERING COMPANY LIMITED, OF TWICKENHAM, ENGLAND PERMANENT METAL FOUNDRY MOLD Application filed September 7, 1928, Serial No. 304,582, and in Great Britain December 14, 1927.

This invention relates to permanent metal foundry molds for the casting of open ended hollow parts having one or more interior isolated or undercut projections intermediate of their length which prevent the metal core of the mold being withdrawn from the open end unless made in a number of sections.

The invention is particularly intended for use in casting aluminium or other alloy trunk pistons in which the gudgeon pin bosses constitute the projecting parts and may also be connected to the crown of the piston by webs of part-annular cross section, although it is also applicable to other objects.

The principal object of the invention is to provide a simplified construction of the core whereby the parts thereof are few in number and initially are easy to assemble accurately and to remove after the casting has been effected.

In the accompanying drawings, which illustrate the application of the invention to the casting of pistons for fluid pressure engines, I

Figure 1 is a vertical section through the plane of the gudgeon pin axis of an unfinished piston for which the mold hereunder described is designed,

Figure 2 is an elevation partly in section 3 on the line IIII of Figure 1 seen in the direction of the gudgeon pin axis,

Figure 3 is a sectional plan on the line of Figure 5,

Figure 8 is a similar plan and cross section of a corresponding part of the mold core indicated by dotted lines in Figure 7. It also shows by dotted lines the relative position of Figure 7.

Figures 9 and 10 are respectively a front and side elevation of the third or looking portion of the core, and

Figure 11 is a cross section of this part on the line XI-XI of Figure 10.

The piston is illustrated in Fi ures 1-4, from which it will be seen that the s irt 2 and the head 3 are integrally formed, while the gudgeon pin bosses 4 are attached to the skirt and constitute the isolated or undercut projections above referred to. Also the bosses 4 are connected with the underside of the piston head by webs 5 of part-annular section, their curvature being concentric with that of the interior of the skirt. 1 They also incline plowgrds one another as they approach the The body 6 of the mold (Figures 5 and 6) may be of usual form having a vertical cylindrical interior 7 conforming to the outside of the piston 2 and divided as at 8 in the axial plane. Separate core pins 9 are provided for the bores of the gudgeon pin bosses 4 and any usual clamping device (not shown) ma be employed for eonnectin the two parts 0 the mold body together and mounting the latter upon its base 10.. r

At the upper end of the mold is a removable ring 11, the lower end of which has a register 12 engaging a recess 13 in the body of the mold, and there are locating pins 14 which correctly position the ring angularly. Above this ring are two additional rings 15 and 16, each havin a spigotal part 17, 18, on its underside to orm a register which enters a recess in the ring below it.

Each of these rings 15 and 16 has depending'from it a longitudinal section of the core as hereunder described. The core actually is formed in three parts, one of which, shown alone at 19 (Figures 9-11) is entirely distinct from the other two parts carried by the rings 15 and 16, its cross section extendin diametrically across the core, the centra portion 20 being narrow and tapered at the sides, while the remaining portions 21 are sector shaped, the planes, of the sides of the sector lying in axial planes of the core, as may be seen from Figure 11. The remaining portion of the. core is divided on an axial plane 22 (Figures 7 and 8) which includes the axis of the gudgeon pin bosses and thus the recess 23 (Figures 5 and 6) formed in the core to provide the bosses, the arrangement being such that each ring 15 and 16 carries a pair of diametrically opposite sections of the core (24 and 25 on the ring 15 and 26 and 27 on the ring 16) although they are integral with one another by their connection with the angularly movable ring. In these respective sections in addition to the recesses 23, others 28 are provided to form the part-annular webs 5 by which the bosses are connected with the crown of the piston.

To prepare the mold for casting. the two parts of the body 6 are clamped together, and the ring 11 is mounted on the upper part of the mold to support the two rings 15 and 16. These are next placed in position, engaging as shown in Figures 7 and 8, and thereafter the section 19 is put into place by a longitudinal movement fitting between the two other sections of the core as shown in Figures 7 and 8 and locking them in position. This section 19 may in turn be locked by any suit able device, such as a tangentially arranged wedge, or the cotter pin 29, extending through the ring 11 at the upper part of the mold. The core pins 9 are then placed in position in the sides of the mold body.

After the metal is poured through the usual gate 80 provided in the moldand the cotter pin 29 is removed, the central section 19 of the core is withdrawn, and, by leverage applied to one of the rings 15 or 16 carrying a section of the core, this latter is turned into the space 31 or 32 made vacant by the removal of the section 19 and is then withdrawn longitudinally from the mold, after which the other ring with its core section is similarly turned and withdrawn. As will be evident, the turning movement withdraws the sections clear of the bosses 4 and the webs 5 of the piston so that they are then free longitudinally. :Ihe mold is then opened to remove the castmg.

From the foregoing it will be seen that the core actually comprises three parts only, and these are so arranged that they can register perfectly with one another and be retained in their correct position simply and expeditiously. As a result, therefore, the casting operations can be carried out with great rapidity and in quick sequence without risk of failure and wastage.

What I claim as my invention and desire to secure by Letters Patent of the United States 18 1. In a permanent metal foundry mold, the combination of a body, a mold cavity formed therein, a core removably mounted in said cavity, a recess in said core adapted to form an internal projection on a casting produced within the mold, longitudinal divisions in said core, one of which extends through said recess therein, and members mounted upon the mold body to rotate about the longitudinal axis of the core, to each of which rotatable members is attached a section of the mold core, substantially asset forth.

2. in a permanent metal foundry mold, the combination of a body, a mold cavity formed therein, a core removably mounted in said cavity, recesses in said core adapted to form diametrically opposite internal projections on a casting produced within the mold, longitudinal divisions in said core thereby to form a freely removable central section and a section on each side thereof having in it a recess adapted to form a projection, through which recesses extend further longitudinal divisions forming thereby two pairs of diametrically arranged sections, and members mounted upon the mold body to rotate about its axis each carrying one pair of the diametrically arranged sections, substantially as set forth.

3. In a permanentmetal foundry mold, the combination of a body, a mold cavity formed therein, a core removably mounted in said cavity, recesses situated in said core on opposite sides thereof adapted to form internal projections on a casting produced within the mold and longitudinal divisions in said core, two of which pass through the recesses separating the core into five longitudinal sections, rings mounted one above the other on said mold body to rotate about the axis of the v core, two diametrically opposite sections of the core being attached to one ring and two to the other ring, the remaining section being freely removable from the mold through the rings, substantially as set forth.

4:. In a permanent metal foundry mold, the combination of a body, a mold cavity formed therein, a core .removably mounted in said cavity formed of three separate parts only but comprising five longitudinal sections, one of which is freely removable while the others in alternate order form pairs having co-operating recesses in their meeting faces, each pair so attached to a ring, and therings so supported by the mold, that after withdrawal of the freely removable part the pairs can be moved angularly to and from one another, substantially as set forth.

5. A permanent metal mold as claimed in claim 4:, in which the freely removable part extends slidably through the two rings and has a cross-section relatively narrow at the centre, widening into sectors at the edges and the cross section tapering lengthwise of the part to facilitate withdrawal from the core, substantially as set forth.

In testimony whereof I have signed my name to this specification.

ERIC GRISP LEWIS. 

